1. Field of the Invention
Embodiments of the present invention relate to an automatic analysis apparatus and an automatic analysis method for analyzing desired examination items e.g., substances contained in an object sample. More particularly, embodiments of the present invention relate to a highly precise automatic analysis apparatus and an automatic analysis method that can variably change an irradiation area or a detection area for analyzing substances contained in the object sample, such as human humor by adjusting an optical conversion point of the irradiation light into the solution based on one or more designated analyzing conditions.
2. Description of the Related Art
An automatic analysis apparatus mainly measures substances contained in humors such as blood or urine with a biochemical assay or an immune serum assay by adding at least one reagent corresponding to the desired examination item. Generally, an automatic analysis apparatus for performing biochemical tests employs spectrophotometry by analyzing changes in color tone due to light absorption of the mixed solution. Alternatively, an automatic analysis apparatus for performing an immune serum assay employs turbidimetry in order to analyze the concentration of a particular substance in an object sample by measuring a turbidity change with scattered light or transmitted light due to an agglutination that is generated by a reaction between an antigen and an antibody in the mixed solution.
In addition to the turbid metric immunoassay, a latex agglutination turbidimetric immunoassay may also be employed to measure a turbidity change of the object sample due to agglutination that is caused by a reaction between an antigen in an object sample and antibody sensitized latex that is sensitized with latex particles. In either of the turbidimetric immunoassays, a reagent is adjusted so as to be applicable for measurements in a particular immune serum test apparatus.
Recently, an increase o in efficiency and a reduction in cost of the biochemical test and the immune serum test are keenly desired. To meet this desire, it would be desirable to perform a plurality of measurements for a plurality of test items including both the biochemical test and the immune serum test in single analyzing apparatus. Particularly, since automatic analysis equipment for biochemical tests can perform processing for many tests of a plurality of measuring items at high speed, it would be desirable to have an automatic analysis apparatus for the immune serum test.
However, when the automatic analysis apparatus for biochemical tests is applied to measure a turbidity change, measurement accuracy and/or precision decrease due to the effects of multiple scatterings of the dispersion objects in the mixed-solution in a reaction cuvette. Thus, if turbidity changes of immune serum examination items are measured by utilizing transmitted light similar to a spectrophotometric test for bio-chemical examination items, the measurement accuracy and/or precision are reduced since a different absorption degree is calculated from the transmitted light through the mixed solution caused by a difference in the effective length of the light path due to the influence of latex concentrated particles scattered in the mixed solution contained in the reaction cuvette.
To improve measurement accuracy and precision through the transmitted light by reducing such influences due to undesired scattered obstacles and to minimize the volume of reaction solution, the applicant has proposed an automatic analysis apparatus that includes two optical convergence lenses provided in front and back of a reaction cuvette in Japanese patent application publication 2003-149157. In the proposed apparatus, an optical convergence point of the optical convergence lens provided in front of the reaction cuvette is set so as to converge at a predetermined distance behind a center position of the reaction cuvette and the optical convergence point of the optical convergence lens provided in the backside of the reaction cuvette is set to coincide with the optical convergence point of the front optical convergence lens. By setting the convergence point of the optical convergence lens behind the reaction cuvette, the influence of scattered light is reduced by restricting detection of the scattered light due to the latex concentrated scattered particles existing in the mixed solution. Accordingly, the accuracy and precision of turbidimetric measurement by the transmitted light can be improved and also the volume of the mixed solution can be minimized.
In the proposed automatic analysis apparatus, the position of a convergence point of an optical convergence lens is determined so as to obtain the maximum amount of light possible in order to measure a designated minimum volume of a mixed solution for the analysis apparatus in accordance with analysis conditions for a particular examination item. However, once the position of the optical convergence point of the optical convergence lens is set, it is always fixed. Accordingly, other measurements for other examination items under different analysis conditions are also performed at the same position of the optical convergence point that was previously set under a particular analysis condition. Thus, when turbidity change is measured by using the transmitted light, the turbidimetric measurement is executed by fixing the optical convergence point of the optical convergence lens at the same point that is appropriated to obtain an irradiation area for the minimum volume of the mixed solution. Consequently, the measurement accuracy and/or precision are reduced by receiving the influence of obstacles, such as bubbles existing in an isothermal bath for covering the reaction cuvette. This is a serous problem for the turbidimetric measurement.